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Biomedical subjects

A Taylor

Publications and source records attributed to A Taylor.

At least 739 records · Page 41Linked to original sources
PubMed1982

Limitations of renal function scanning in acute obstruction.

This study was designed to determine if technetium-99m penicillamine (TPEN), could be used to predict recoverable function in dogs with acute obstruction. Renal accumulation of TPEN was measured in four control dogs, in four dogs with acute obstruction lasting 7-14 days, and in the same four dogs following a variable recovery period of 15-63 days. The relative renal uptake of TPEN in vivo showed good agreement with the relative uptake in vitro and both measurements correlated closely with the relative inulin clearances in the normal and in the post obstructed kidneys. The uptake of TPEN in the obstructed kidney following 7-14 days of obstruction averaged 6.8% of the total renal uptake. After relief of the obstruction and a variable recovery period the relative uptake of TPEN in the post obstructed kidney had increased to a mean of 29.5%. These results indicate that TPEN scans should not be used during acute obstruction to predict recoverable function. The observations noted in the study almost certainly apply to similar chelating agents such as dimercaptosuccinic acid (DMSA) and probably to other renal radiopharmaceuticals as well.

Animals↗
PubMed1982

Interrelationship of serum 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D in juvenile renal osteodystrophy after therapy with 25-hydroxyvitamin D3.

The interrelationship of circulating 25(OH)D3 and 1,25(OH)2D in children with uremic renalosteodystrophy has been examined in 19 patients treated for 1 to 4 yr with 25(OH)D3. There was a direct correlation between 25(OH)D3 and 1,25(OH)2D levels when the GFR was less than or equal to 25 but not greater than 25 ml/min/1.73m2 (r = 0.47, P = less than .01). This correlation was unchanged when 1,25(OH)2D was factored by serum phosphorus or serum creatinine but became nonsignificant when 1,25(OH)2D was factored by serum bicarbonate. Overall, parathyroid hormone (PTH) did not change the correlation. However, when the data were subdivided by levels of glomerular filtration rate (GFR) and PTH, the correlation between 25(OH)D3 and 1,25(OH)2D was significant only when GFR was less than or equal to 25 and the PTH was markedly elevated (P = less than .01), suggesting that a substantial elevation of PTH may be necessary to stimulate 1,25(OH)2D production in these patients. Individual 1,25(OH)2D levels measured over time (1-4 yr) fluctuated regardless of GFR. Despite high serum 25(OH)D3 levels after 25(OH)D3 therapy, there was no consistent increase in the 1,25(OH)2D levels, and many posttreatment levels were lower than pretreatment levels. The kinetics of 1,25(OH)2D metabolism failed to reveal a progressive increase in the serum levels between 2 and 24 hours after a pharmacologic dose of 25(OH)D3.

Adolescent↗
PubMed1982

Synthesis and localization of two sulphated glycoproteins associated with basement membranes and the extracellular matrix.

Two sulphated glycoproteins (sgps) of apparent molecular weight (Mr) 180,000 and 150,000, are synthesized by murine PYS and PF HR9 parietal endoderm and Swiss 3T3 cells. The Mr 150,000 sgp has a similar chemical structure to the sulphated glycoprotein, C, synthesized and laid down in Reichert's membrane by mouse embryo parietal endoderm cells (Hogan, B. L.M., A. Taylor, and A.R. Cooper, 1982, Dev. Biol., 90:210-214). Both the Mr 180,000 and 150,000 sgps are deposited in the detergent-insoluble matrix of cultured cells, but they do not apparently undergo any disulphide-dependent intermolecular interactions and are not precursors or products of each other. They contain asparagine-linked oligosaccharides, but these are not the exclusive sites of sulphate labeling. Antiserum raised against the Mr 150,000 sgp C of Reichert's membranes has been used in an immunohistochemical analysis of rat skin. In early foetal and adult skin the antigen is present only in basement membranes, but transiently before and after birth it is also found throughout the upper part of the dermis. This suggests that 150,000 sgp C is at times synthesized by nonepithelial cells and contributes to the extracellular matrix of mesenchymal tissues.

Animals↗
PubMed1982

Ovine ill-thrift in Nova Scotia. 9. Production of experimental quantities of isocyanide metabolites of Trichoderma hamatum.

Laboratory cultures of Trichoderma hamatum produce metabolites that are characterized by an isocyanide functionality. Three such metabolites predominate. One is the known compound trichoviridin (I). The other two, described here for the first time, are 3-(3-isocyano-6-oxabicyclo[3,1,0]hex-2-en-5-yl)acrylic acid (II) and a very unstable compound 3-(3-isocyanocyclopent-2-enylidene-)propionic acid (III). Production of these three metabolites by a random sample of wild isolates of the fungus has been examined. At least one of these isocyanides was isolated from all cultures in which the culture broth inhibited the growth of Micrococcus luteus. The relative amounts of the three isocyanides produced by individual isolates were not the same and cultures were found in which I, II, or III was the main product. The isocyanide III was produced by all wild isolates which had antibiotic activity in their culture broth, and it was present in the concentration range 2-40 mg X L-1.

Antibodies, Fungal↗
PubMed1982

Abnormal 99mTc-PIPIDA scans mistaken for common duct obstruction.

99mTc-PIPIDA scans were obtained in three patients with acute abdominal pain. The appearance of the scans suggested partial common duct obstruction. Two patients underwent surgery. One had acute appendicitis and the second had infarction of the distal ileum. In both cases, the gallbladder and biliary tract were normal. The third patient had been treated with morphine, which is known to increase biliary tract pressure and may cause contraction of the sphincter of Oddi. An ultrasound study of the gallbladder was normal and all symptoms resolved within 24 hours. Subsequently, three additional patients without biliary disease have been seen who had similar hepatobiliary scans. All three had received meperidine prior to the study. It is concluded that acute abdominal disease or the administration of morphine sulfate or meperidine can result in a scan pattern suggesting partial distal common duct obstruction in the absence of gallbladder or biliary tract disease.

Abdomen, Acute↗
PubMed1982

Hydroosmotic response of collecting tubules to ADH or cAMP at reduced peritubular sodium.

Changes in cytosolic Ca2+ activity have been implicated in the hydroosmotic response to vasopressin (VP) in amphibian urinary bladder; the level of cytosolic free Ca2+ may be regulated, in part, by a process of Na-Ca exchange across the basolateral cell membrane. To assess whether similar mechanisms operate in the mammalian nephron, the effect of low peritubular [NA] on the hydraulic conductivity (Lp) of the isolated perfused rabbit collecting tubule (CT) exposed to either 20 microunits/ml VP or 5 X 10(-5) M 8-[p-chlorophenylthio]-cyclic 3',5'-adenosine monophosphate (ClPheS-cAMP) was studied. Low peritubular [Na] had no effect on the basal water permeability of the CT. After exposure to VP, CTs bathed in 145 mM Na Ringer solution developed an Lp of 324 +/- 27 X 10(-7) cm.s-1.atm-1, while tubules bathed in 4 mM Na and 141 mM tetramethylammonium Ringer solution achieved an Lp of only 112 +/- 13 X 10(-7) cm.s-1.atm-1 (P less than 0.001). Inhibition of the VP response was estimated to be half-maximal when peritubular Na was 120 mM. The hydroosmotic response to ClPheS-cAMP was diminished by 44% of the control values when CTs were bathed in a 4 mM Na medium; this inhibition was greatly attenuated when the peritubular Ca concentration was reduced to 0.05 mM. These results are consistent with the view that 1) a Na-Ca exchange process operates at the basolateral surface of the mammalian cortical collecting tubule cells, and 2) elevated cytosolic Ca ion activity inhibits the increase in water permeability elicited by VP or cAMP in this nephron segment.

Animals↗
PubMed1982

Identification and quantification of leucine aminopeptidase in aged normal and cataractous human lenses and ability of bovine lens LAP to cleave bovine crystallins.

Rabbit antisera to bovine lens leucine aminopeptidase (LAP) have been prepared. These LAP-specific antisera cross-react with a component, LAP, in human lens homogenates. Bovine and human lens LAP are similar but not identical. Immunodiffusion tests show that LAP is present in a vast majority if not all cataractous and normal human lens homogenates. Results from immunoelectrophoresis indicate that LAP is found in these homogenates as several metazymes as well as in an albuminoid--and possibly membrane-associated form. In contrast to many activity-based studies which imply that very little LAP is present in human lenses, micro-complement fixation tests indicate that the concentration of LAP in aged human lenses is similar to that found in calf lenses. Taken together, these data indicate that LAP undergoes age-related changes. These alterations of enzyme (or environment) result in an enzyme of markedly reduced activity, hence, the discrepancy between amount of LAP and the amount of enzymatic activity in aged human lenses. Active LAP is shown to enhance the rate of hydrolysis of alpha-2 and alpha-B crystallins but not alpha-A2, beta H, beta L or gamma crystallins. The ramifications of LAP inactivation with respect to cataractogenesis are discussed.

Adult↗
PubMed1981

Ovine ill-thrift in Nova Scotia. 7. Trichoderma hamatum isolated from pasture soil.

Trichoderma hamatum accounts for about 1.5% of the fungal propagules isolated from pasture soil at Nappan, Nova Scotia. Greater numbers of propagules of this fungus were isolated in June and September than in July, August and October, with the apparent optimum growth temperature in the field being about 18 degrees C. Unlike the fungal flora collected, propagules of T. hamatum were not randomly distributed throughout the experimental plot. Fifty three percent of isolates of T. hamatum (or 1% of the fungal propagules isolated) in laboratory culture produced toxic, water-soluble metabolites. Two of these metabolites are isonitrile acids.

Animals↗
PubMed1981

Comparison of procedures for determination of copper and zinc in serum by atomic absorption spectroscopy.

Methods used to prepare serum samples for the determination of copper and zinc by atomic absorption spectroscopy have been compared using the results obtained from an external quality control scheme. The methods most commonly employed were dilution with water, dilution with dilute butan-1-ol or propan-1-ol, removal of protein by trichloroacetic acid (TCA) precipitation and electrothermal atomization (ETA). The effects of the inclusion of sodium and potassium ion upon results has been examined. Low results for serum copper are given by the technique of ETA. High zinc values are found following TCA precipitation. None of the methods showed superior between-batch precision. Ionization interference was variable and the addition of sodium and potassium to standard solutions is not always necessary.

Copper↗